Phil, I don't want to through a spanner in the works but if you're using Hornby's 31 111 as a starting point for your pre-Tops blue 'un you might have to get the scalpel out... IIRC that body moulding has the bodyside steps plated over and possibly the roof boiler hatch too.... as far as I can make out these areas weren't plated over till at least 1975, by which time of course the class were well into their Tops numbered phase.... !
Fascinating thread though!
Nidge